In recent years, a technique of configuring a thin film transistor (TFT) by using a semiconductor thin film (a thickness of about several nanometers to several hundred nanometers) which is formed over a substrate having an insulating surface attracts attention. A thin film transistor is widely applied to an electronic device such as an IC and an electro-optical device, and there is an urgent need for the development particularly as a switching element of an image display device.
Conventionally, a liquid crystal display device is known as an image display device. An active matrix liquid crystal display device is used more often than a passive matrix liquid crystal display device since a higher-definition image can be obtained compared to the passive matrix liquid crystal display. In an active matrix liquid crystal display device, a display pattern is formed on screen by driving a pixel electrode arranged in matrix. More specifically, by applying a voltage between a selected pixel electrode and a counter electrode corresponding to the pixel electrode, a crystalline layer which is disposed between the pixel electrode and the counter electrode is modulated optically, and the optical modulation is recognized as a display pattern by an observer.
Application of thus active matrix electro-optical device has been widened, and the demand on high definition, high aperture ratio and high reliability has been increased along with the demand on large area of screen size.
Till now, production engineering has been adopted in which a liquid crystal display panel is mass produced efficiently by cutting out a plurality of liquid crystal display panels from one mother glass substrate. Size of a mother glass substrate is enlarged from 300×400 mm of the first generation in the early 1990s to 680×880 mm or 730×920 mm of the fourth generation in 2000, and a plurality of the display panel can be obtained from one mother glass substrate.
In addition, the demand on improved productivity and lower cost has been increased along with the demand on large area of screen size.
In addition, in recent years, researches on a light emitting device comprising an EL element as a self-luminous light emitting element has been activated. The light emitting device is also referred to as an organic EL display or an organic light emitting diode. The light emitting devices have characteristics such as high response speed which is suitable for displaying moving images, low voltage drive, and low power consumption drive. Therefore, the light emitting devices has been attracting attention as a next-generation displays including new-generation cellular phones, personal digital assistants (PDA) and the like.
An EL element including a layer containing an organic compound as a light-emitting layer has the structure in which the layer containing an organic compound (hereinafter referred to as EL layer) is interposed between an anode and a cathode. Upon applying electric field to the anode and cathode, luminescence (Electro Luminescence) is emitted from the EL layer. In addition, luminescence from the EL element includes luminescence (fluorescence) in returning from a singlet excited state to a ground state and luminescence (phosphorescence) in returning from the triplet excited state to the ground state.
Application of thus active matrix display device has been widened, and the demand on high definition, high aperture ratio and high reliability has been increased along with the demand on large area of screen size.
Referring to Japanese Patent Laid-Open No. 2000-298446, a large-sized display is realized by disposing a plurality of panels like tiles to form one display screen. However, the cost is high since a plurality of panels is used, and a driving method becomes special.
In addition, the demand on improve3d productivity and lower cost has been increased along with the demand on large area of screen size.
Additionally, the technique is described in Japanese Patent Laid-Open No. 2000-188251, in which film formation is conducted over a semiconductor wafer by using an apparatus capable of continually discharging liquid resist with a linear shape of small diameter from a nozzle in order to increase yield of liquid which is used as film formation.